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Apache HTTP Server Version 2.4
Apache > HTTP Server > Documentation > Version 2.4 > Modules
Apache Module mod_heartbeat
Description: Sends messages with server status to frontend proxy Status: Experimental Module Identifier: heartbeat_module Source File: mod_heartbeat Compatibility: Available in Apache 2.3 and later
Summary
mod_heartbeat sends multicast messages to a mod_heartmonitor listener that advertises the servers current connection count. Usually, mod_heartmonitor will be running on a proxy server with mod_lbmethod_heartbeat loaded, which allows ProxyPass to use the "heartbeat" lbmethod inside of ProxyPass.
mod_heartbeat itself is loaded on the origin server(s) that serve requests through the proxy server(s).
To use mod_heartbeat, mod_status and mod_watchdog must be either a static modules or, if a dynamic module, must be loaded before mod_heartbeat.
Topics
Directives
Bugfix checklist
See also
Consuming mod_heartbeat Output
Every 1 second, this module generates a single multicast UDP packet, containing the number of busy and idle workers. The packet is a simple ASCII format, similar to GET query parameters in HTTP.
An Example Packet
v=1&ready=75&busy=0
Consumers should handle new variables besides busy and ready, separated by '&', being added in the future.
HeartbeatAddress Directive
Description: Multicast address for heartbeat packets Syntax: HeartbeatAddress addr:port Default: disabled Context: server config Status: Experimental Module: mod_heartbeat The HeartbeatAddress directive specifies the multicast address to which mod_heartbeat will send status information. This address will usually correspond to a configured HeartbeatListen on a frontend proxy system.
HeartbeatAddress 239.0.0.1:27999